But, this move seems to make little sense in the long-term. The PowerPc architecture has proven time and time again to be superior in many ways, both from a usability standpoint and from a performance standpoint. Apple also loses the AltiVec, which is responsible for much of the high-end performance characteristics of their boxes.

What could Apple be thinking?

Word is that any further increase in clock speed for the G5 line requires an exponential increase in power requirements, making them unsuitable for the PowerBook line. Quite a surprise, since the PowerPc has historically had a better power/performance ratio than Intel's chips.

And in general there has been evidence for some years that Moore's Law has been running out of steam already, so that the clock speed of a single processor is not expected to be anywhere near so important in the future, beginning with approximately Fall 2005. -- DougMerritt

Of course, Apple is fortunate that MacOsxIsUnixBased and that NextStep aka CocoaFramework has been kept compatible with the Intel architecture. Otherwise, they wouldn't even have the option to switch.

A couple of possibilities come to mind:

Doubts about the ability of Motorola/Freescale and IBM to supply parts, and keep up with continuing improvements in the Intel line. Mot/Freescale is probably not a reliable partner anymore; and given that IBM is in many ways a competitor, this is a concern. Intel is not a competitor; and AMD is a possible second source.

Apple may have long-term plans to compete with Windows (and Linux) as a standalone PC operating system.

Better Windows/Linux emulation environments?

Plus, I'm curious in what way you think the processor architecture (PowerPC vs Intel) affects usability. Unless you're an assembly-language programmer, I can't think of any way that this has any impact on the end user. The reasons Apple generally wins on usability have nothing to do with the processor per se. Instead, it's because:

Apple is a more tightly-controlled system, so a lot of the integration headaches PC users have to deal with are simply not problems in the Apple world. (On the opposite side of the coin; the PC user has many more choices).

Many of the legacy bus architectures requiring manual configuration, which have long plagued the PC, have gone away. On both platforms, you'll find USB, FireWire, PCI, etc.... all PlugAndPlay systems. RS-232, Centronics, ISA bus, etc. have long been banished from new PCs.

MacOS is a far superior product (on the usability front) to any Windows or Linux version you'll find. The underlying MACH/BSD kernel is certainly better than any MS system; and comparable to Linux (many consider it better; others don't). It's a flavor of Unix, anyway, so no need to beat a dead horse.

About the only thing the user notices that the CPU might affect is the power/noise issue; PowerPcs have historically consumed less power so don't need fans that sound like Indy cars.

Well, I know that Apple has enjoyed a profitable relationship with scientific computing institutions. Simply put, for scientific computing there isn't much that beats a mac. It's usable, easy to maintain, and packs a whallop when you code specifically for it. I know my company made a choice based almost solely on performance.

Since Apple has found a lot of surprising instances where things reduce to altivec problems (searching your email, for example), I can't help but think that this means some tasks on MacOS X will run more slowly than on the G5 counterparts. Unless, of course, Intel has some piece of comparable technology, a whole new processor targeted for workstations. -- DaveFayram

The frequent comment is that the biggest problem with both Altivec and MMX is getting developers to use them at all.

Let's not forget the marketing angle: Apple has been getting beaten-up silly over the years when people realize they can get a Dell with a Celeron running at 2 GHz for about 20% of the price of a G5 running at 2 GHz. Never mind what the processing power actually is. People just see that clockspeed number. -- AndyPierce

AMD, faced with the same problem (for many years they've been much cooler and much faster than Intel Pentiums at the same clock speed) did pretty well solving it by labelling their chips with the Pentium clock speed equivalent, e.g. "2000+" for something that they regard (usually quite accurately) as being as fast as a 2Ghz Pentium, even if it's running at 1.2Ghz or some such.

Actually, this is just Apple returning to their roots.

Their first widespread success, the AppleIi, ran on a 6502 processor - a LittleEndian machine. (The only place endian-ness mattered on the 6502, an 8-bit machine, was in the load/store instructions which encoded the target address - a 16-bit number - in the opcode. It was LSB first, MSB second).

It also mattered for the instructions that did indirect addressing through a zero page location.

Now, with the forthcoming switch to the LittleEndian i32 architecture; they've come full circle. One wonders if this will mean the eventual DeathOfBigEndian?...
Given the relative stagnation of the Macintosh line since the switch, this is looking less like a way for Apple to compete in the larger PersonalComputer market, and more like a way for them to gracefully stop making computers altogether and concentrate on the more profitable iPad and iPhone.

Or become one-in-the-same. A "Macintosh" will merely be an iPad with a keyboard plugged into it.